Many products are stored in individual containers, the containers then being stacked on one another on a warehouse floor or on pallets. To provide stability for the stack, several things can be done. One common approach is to bind together all the containers stacked on a pallet. This is often done, for example, when the containers are cardboard boxes each containing bottled beverages.
Another method for increasing the stability of a stack of containers is to stagger the containers in adjacent levels similar to the way a mason staggers bricks when building a brick wall. Although the staggered approach produces stacks of containers which are much more stable than stacks having vertical columns of containers, shifting is still possible between the various levels of boxes and between the containers in individual levels. Another drawback with staggered stacks is that they do not readily lend themselves to automatic stacking since the containers in each level are placed in locations different from the adjacent level. Also, the geometry of the containers may not lend itself to this sort of stacking.
A third method used to improve stability is to extend a projection from the top of the container to prevent lateral shifting of the overlying containers. Although this helps to prevent shifting of containers in one horizontal direction, it may not prevent shifting in a transverse direction nor does it interlock one column of containers with another column of containers.
In some situations the containers in which a product or material is shipped are reusable and therefore must be returned. To reduce the inefficiency of transporting a load of empty containers, it is desirable that the containers be collapsible or nesting to reduce the space they occupy. However, the requirement of a container being stackable, interlockable and nestable has not been available.